Vegetation Analysis and Species Diversity Along an Altitudinal Gradient in the Central Hijaz Mountains of Saudi Arabia PDF

Keywords

Plant communities, diversity, altitudinal gradient, vegetation, Hijaz Mountains, Saudi Arabia.

Abstract

The study deals with the distribution, habitats, and ecological characteristics of natural vegetation along a transect crossing the central part of Hijaz Mountains, Saudi Arabia. Fifty stands were classified on the basis of leading dominant species, using agglomerative cluster analysis, into five distinct and recognizable vegetation groups (vegetation types). A total of 86 plant species were recorded. The present study provides evidence that the vegetation shows discernible zonation. The annuals increase, and the biennials and perennials decrease along the elevation gradient from lower to higher elevations. This appears to be correlated, at least partly, with altitude. Species diversity varies from one vegetation group to the other as well as between stands of the same group. The vegetation type of Ficus salicifolia is the most widespread, diversified and consequently, the most stable vegetation cover in the study area; it, therefore, represents the climatic climax community. Human interference has a prominent role in changing the physical environment and inevitably destroys the precarious balance among the components of the ecosystem. The environment has deteriorated, and retrogressive changes in the vegetation are recorded.